1. Field of Invention
Various embodiments of the present invention relate to a semiconductor device and, more specifically, to a semiconductor device including a memory string.
2. Description of Related Art
A memory string of three-dimensional structure includes memory cells, vertically stacked on a substrate, and select transistors. Unlike the two-dimensional structure, a select transistor having a three-dimensional structure may be formed using the same structure as a memory cell. That is, the select transistor may include a charge storage layer. For this reason, an erase operation, a program operation and a verify operation may be performed to adjust the threshold voltage of the select transistor. Due to features of the three-dimensional structure, an error may occur when a verify operation on the select transistor is performed.